Isobutyric ester compound having propanoyloxy group at alpha-position, fragrance composition, and use thereof as fragrance

ABSTRACT

A fragrance composition comprising a compound represented by Formula (1) as an active ingredient:wherein, in Formula (1), R1 represents a linear, branched, or cyclic alkyl group having 1 to 5 carbon atoms.

TECHNICAL FIELD

The present invention relates to isobutyric ester compounds having apropanoyloxy group at the α-position, fragrance compositions, and usethereof as a fragrance composition.

BACKGROUND ART

Some isobutyric esters are known to be compounds useful as fragrances.For example, Non Patent Document 1 describes that various isobutyricesters are mainly used as flavors, and all these isobutyric esters areflavor materials having a fruit scent; specifically, methyl isobutyrategives a sweet apricot-like scent, propyl isobutyrate gives a strongpineapple-like scent, butyl isobutyrate gives a fresh apple- andbanana-like scent, and isoamyl isobutyrate gives a sweet apricot- andpineapple-like scent.

Additionally, Patent Document 1 discloses that, as an isobutyric esterhaving a bond with oxygen at the α-position, a linear or branched alkylester having 4 to 12 carbon atoms of α-alkoxyisobutyric acid is usefulas a fragrance, and n-hexyl α-ethoxyisobutyrate has a lavender-likearoma.

On the other hand, Non Patent Document 2 describes that methylα-propanoyloxyisobutyrate is obtained by methylating an oxidized productof a specific furanone compound with diazomethane, but there is nodescription about the aroma characteristics thereof, fragrancecompositions comprising the same, and further, methods for use as afragrance.

CITATION LIST Patent Documents

-   Patent Document 1: U.S. Pat. No. 3,368,943

Non Patent Document

-   Non Patent Document 1: “Gousei Koryo: Kagaku to Shohin Chishiki,    zoho shinban (Synthetic fragrance: chemistry and product knowledge,    new enlarged edition)”, The Chemical Daily Co. Ltd., 2016, pp. 580    to 582-   Non Patent Document 2: Canadian Journal of Chemistry, 1984, vol. 62,    pp. 2429-2434

DISCLOSURE OF THE INVENTION Technical Problem

An object to be solved by the present invention is to provide anisobutyric ester compound having a propanoyloxy group at the α-position,useful as a fragrance and a fragrance ingredient. Further, anotherobject to be solved by the present invention is to provide a fragrancecomposition containing an isobutyric ester compound having apropanoyloxy group at the α-position as an active ingredient and use ofthe compound as a fragrance.

Solution to Problem

The present inventors have synthesized various compounds and have made adiligent research of the aromas thereof. Thus, the present inventorsdiscovered that particular ester compounds of isobutyric acid having apropanoyloxy group at the α-position are useful as fragrances andfragrance ingredients.

That is, the present invention is as follows.

<1> A fragrance composition comprising a compound represented by Formula(1) as an active ingredient:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclicalkyl group having 1 to 5 carbon atoms.

<2> The fragrance composition according to <1>, wherein, in Formula (1),R¹ is selected from the group consisting of a methyl group, an ethylgroup, a n-propyl group, an isopropyl group, a n-butyl group, anisobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and acyclopentyl group.

<3> Use of a compound represented by Formula (1) as a fragrance:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclicalkyl group having 1 to 5 carbon atoms.

<4> The use according to <3>, wherein, in Formula (1), R¹ is selectedfrom the group consisting of a methyl group, an ethyl group, a n-propylgroup, an isopropyl group, a n-butyl group, an isobutyl group, asec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.

<5> The use according to <3> or <4>, wherein the compound represented byFormula (1) imparts a mint-like scent.

<6> The use according to <3> or <4>, wherein the compound in which R¹ isan isopropyl group in Formula (1) imparts a damascone-like fruity-tone,floral-tone, or woody-tone scent.

<7> A compound, represented by Formula (2):

wherein, in Formula (2), R² represents a linear, branched, or cyclicalkyl group having 2 to 5 carbon atoms.

<8> The compound according to <7>, wherein, in Formula (2), R² isselected from the group consisting of an ethyl group, a n-propyl group,an isopropyl group, a n-butyl group, an isobutyl group, a sec-butylgroup, a 3-methylbutan-2-yl group, and a cyclopentyl group.

<9> The compound according to <7> or <8>, wherein, in Formula (2), R² isan ethyl group.

<10> The compound according to <7> or <8>, wherein, in Formula (2), R²is a n-propyl group.

<11> The compound according to <7> or <8>, wherein, in Formula (2), R²is an isopropyl group.

<12> The compound according to <7> or <8>, wherein, in Formula (2), R²is a n-butyl group.

<13> The compound according to <7> or <8>, wherein, in Formula (2), R²is an isobutyl group.

<14> The compound according to <7> or <8>, wherein, in Formula (2), R²is a sec-butyl group.

<15> The compound according to <7> or <8>, wherein, in Formula (2), R²is a 3-methylbutan-2-yl group.

<16> The compound according to <7> or <8>, wherein, in Formula (2), R²is a cyclopentyl group.

Advantageous Effects of Invention

According to the present invention, it is possible to provide anisobutyric ester compound having a propanoyloxy group at the α-position,useful as a fragrance and a fragrance ingredient. Further, according tothe present invention, it is possible to provide a fragrance compositioncontaining an isobutyric ester compound having a propanoyloxy group atthe α-position as an active ingredient and use of the compound as afragrance.

DESCRIPTION OF EMBODIMENTS

[Fragrance Composition and Use]

A fragrance composition of the present invention comprises a compoundrepresented by Formula (1) below as an active ingredient. Furthermore,use of the present invention is use of the compound represented byFormula (1) below as a fragrance.

The present invention will be described in detail hereinbelow.

<Compound Represented by Formula (1)>

The compound to be used in the fragrance composition of the presentinvention and the use of the present invention is represented by Formula(1) below:

wherein, in Formula (1), R¹ represents a linear, branched, or cyclicalkyl group having 1 to 5 carbon atoms.

In Formula (1), specific examples of R¹ include a methyl group, an ethylgroup, a n-propyl group, an isopropyl group, a n-butyl group, anisobutyl group (2-methylpropyl group), a sec-butyl group (1-methylpropylgroup), a tert-butyl group, a n-pentyl group, a 1-methylbutyl group(2-pentyl group), a 2-methylbutyl group, a 3-methylbutyl group, aneopentyl group (2,2-dimethylpropyl group), a 2-methylbutan-2-yl group,a 1-ethylpropyl group (3-pentyl group), a 3-methylbutan-2-yl group, acyclopropyl group, a cyclobutyl group, and a cyclopentyl group.

When the R¹ group has an asymmetric carbon, the compound represented byFormula (1) includes any one of optical isomers resulting from theasymmetric carbon or a mixture of the isomers at any proportion.

The compound represented by Formula (1), which is useful as a fragranceand a fragrance ingredient, has a mint-like aroma as well assimultaneously exhibits an aroma of a woody tone, spicy tone, floraltone, or the like due to the difference in the alkyl groups (R¹) of theester moiety.

The compound is preferably a compound in which R¹ is selected from thegroup consisting of a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, an isobutyl group, a sec-butyl group,a 3-methylbutan-2-yl group, and a cyclopentyl group. The compound isalso preferably a compound in which R¹ is selected from the groupconsisting of a methyl group, an ethyl group, a n-propyl group, anisopropyl group, a n-butyl group, an isobutyl group, and a cyclopentylgroup.

Particularly preferably, R¹ is a methyl group.

Particularly preferably, R¹ is an ethyl group.

Particularly preferably, R¹ is a n-propyl group.

Particularly preferably, R¹ is an isopropyl group.

Particularly preferably, R¹ is a n-butyl group.

Particularly preferably, R¹ is an isobutyl group.

Particularly preferably, R¹ is a sec-butyl group.

Particularly preferably, R¹ is a 3-methylbutan-2-yl group.

Particularly preferably, R¹ is a cyclopentyl group.

In an embodiment of the present invention, examples of the compoundrepresented by Formula (1) include a compound represented by any ofFormulas (1-1) to (1-19) below, and particularly preferable compoundsinclude a compound represented by any of Formulas (1-1) to (1-8), and(1-18) below.

In recent years, there is a trend to focus more on the toxicity andenvironmental impact of chemicals, and fragrances or fragrancecompositions are no exception. There is an increase in the number ofcases where a fragrance which has been used in the past is severelyrestricted in usage conditions or is prohibited from use due to theirsensitization properties to a human body, tendency to accumulate in theenvironment, and the like. Thus, there is a strong demand for afragrance and a fragrance composition having a lower environmentalimpact. Accordingly, the fragrance ingredient preferably has excellentbiodegradability.

The compound represented by Formula (1) contains a compound excellent inbiodegradability, and from the perspective of biodegradability, R¹ ispreferably a group selected from the group consisting of a methyl group,an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group,an isobutyl group, a sec-butyl group, a 3-methylbutan-2-yl group, and acyclopentyl group. Additionally, from the same perspective, R¹ ispreferably a group selected from the group consisting of a methyl group,an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group,an isobutyl group, and a cyclopentyl group.

The compound represented by Formula (1) is useful as a fragrance becausethe compound has an excellent aroma as described below. Generally, afragrance is rarely used alone, and often used in a fragrance compound(fragrance composition) produced by compounding a plurality offragrances in accordance with the purpose. The compound represented byFormula (1) is useful as a fragrance (also called a “fragranceingredient”) to be blended in a fragrance compound (fragrancecomposition), and the fragrance composition of the present inventioncontains the compound represented by Formula (1) as an activeingredient. As the fragrance, one of the compounds represented byFormula (1) above may be used alone or two or more of the compounds maybe used in combination.

Additionally, the compound represented by Formula (1) may include asmall amount of impurities, by-products, contaminants, and the like aslong as the effects of the present invention are not compromised.

The compound represented by Formula (1) has a mint-like aroma as well asan aroma of woody-tone, spicy-tone, floral-tone, or like, and also isexcellent in diffusivity. Further, the compound represented by Formula(1-4) has a damascone-like fruity-tone, floral-tone, or woody-tonearoma, and also is excellent in diffusivity.

The compound represented by Formula (1) may be used alone as a fragranceand added to various perfumery and cosmetics, healthcare and sanitarymaterials as well as medicinal supplies, household goods, foods, and thelike to thereby impart an aroma thereto. Alternatively, the compoundrepresented by Formula (1) may be mixed with another fragranceingredient or the like to prepare a fragrance composition (fragrancecompound) described below, which may be blended into a variety ofproducts to impart an aroma. Among these, from the perspective ofobtaining an intended aroma, it is preferred that the compoundrepresented by Formula (1) be blended in a fragrance composition as afragrance ingredient to prepare a fragrance composition containing thecompound represented by Formula (1) as an active ingredient and thefragrance composition be blended in a product to perfume the product.

Additionally, the compound represented by Formula (1) is preferably usedas a fragrance and is more preferably used to impart a mint-like scent.Furthermore, the compound represented by Formula (1-4) is morepreferably used to impart a damascone-like fruity-tone, floral-tone, orwoody-tone scent.

<Fragrance Composition>

The fragrance composition (fragrance compound) of the present inventioncontains the compound represented by Formula (1) as an activeingredient. Note that the fragrance composition is not particularlylimited as long as that it contains at least one compound represented byFormula (1), and two or more compounds represented by Formula (1) may beincluded.

The fragrance composition according to an embodiment of the presentinvention is only required to contain the compound represented byFormula (1) as an active ingredient, and other ingredients are notparticularly limited. However, the fragrance composition preferablycontains another fragrance ingredient (hereinafter, also referred to asa “known fragrance”).

Note that the “fragrance composition (fragrance compound)” is acomposition that is added to various perfumery and cosmetics, medicinalsupplies, foods, beverages, and the like to impart an aroma thereto, ora composition that is used as it is in a perfume or the like. Thefragrance composition may contain an additive such as a solvent, asrequired, in addition to the known fragrance.

The amount of the compound represented by Formula (1) blended depends onthe type of the compound, the type of aroma intended, the intensity ofthe aroma, and the like. The amount of the compound represented byFormula (1) in the fragrance composition is preferably 0.001 mass % orgreater, more preferably 0.01 mass % or greater, even more preferably0.1 mass % or greater, and preferably 90 mass % or less, more preferably70 mass % or less, and even more preferably 50 mass % or less.

The known fragrance is not particularly limited as long as it is a knownfragrance component, and a wide range of fragrances can be used. Forexample, one or two or more of the following fragrances can be selectedand used at any mixing ratio.

Examples thereof include hydrocarbons such as limonene, α-pinene,β-pinene, terpinene, cedrene, longifolene, and valencene; alcohols suchas linalool, citronellol, geraniol, nerol, terpineol, dihydromyrcenol,ethyllinalool, farnesol, nerolidol, cis-3-hexenol, cedrol, menthol,borneol, β-phenylethyl alcohol, benzyl alcohol, phenyl hexanol,2,2,6-trimethylcyclohexyl-3-hexanol,1-(2-t-butylcyclohexyloxy)-2-butanol, 4-isopropylcyclohexane methanol,4-t-butylcyclohexanol,4-methyl-2-(2-methylpropyl)tetrahydro-2H-pyran-4-ol,2-methyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-butene-1-ol,2-ethyl-4-(2,2,3-trimethyl-3-cyclopenten-1-yl)-2-buten-1-ol,isocamphylcyclohexanol, and 3,7-dimethyl-7-methoxyoctane-2-ol; phenolssuch as eugenol, thymol, and vanillin; esters such as linalyl formate,citronellyl formate, geranyl formate, n-hexyl acetate, cis-3-hexenylacetate, linalyl acetate, citronellyl acetate, geranyl acetate, nerylacetate, terpinyl acetate, nopyl acetate, bornyl acetate, isobronylacetate, o-t-butylcyclohexyl acetate, p-t-butylcyclohexyl acetate,tricyclodecenyl acetate, benzyl acetate, styralyl acetate, cinnamylacetate, dimethylbenzylcarbinyl acetate, 3-pentyltetrahydropyran-4-ylacetate, citronellyl propionate, tricyclodecenyl propionate,allylcyclohexyl propionate, ethyl-2-cyclohexyl propionate, benzylpropionate, citronellyl butyrate, dimethylbenzylcarbinyl n-butyrate,tricyclodecenyl isobutyrate, methyl-2-nonenoate, methyl benzoate, benzylbenzoate, methyl cinnamate, methyl salicylate, n-hexyl salicylate,cis-3-hexenyl salicylate, geranyl tiglate, cis-3-hexenyl tiglate, methyljasmonate, methyldihydro jasmonate, methyl-2,4-dihydroxy-3,6-dimethylbenzoate, ethylmethylphenyl glycidate, methyl anthranilate, andFRUITATE; aldehydes such as n-octanal, n-decanal, n-dodecanal,2-methylundecanal, 10-undecenal, citronellal, citral,hydroxycitronellal, dimethyl tetrahydrobenzaldehyde,4(3)-(4-hydroxy-4-methylpentyl)-3-cyclohexene-1-carboaldehyde,2-cyclohexyl propanal, p-t-butyl-α-methylhydrocinnamic aldehyde,p-isopropyl-α-methylhydrocinnamic aldehyde,p-ethyl-α,α-dimethylhydrocinnamic aldehyde, α-amylcinnamic aldehyde,α-hexylcinnamic aldehyde, piperonal, andα-methyl-3,4-methylenedioxyhydrocinnamic aldehyde; ketones such asmethylheptenone, 4-methylene-3,5,6,6-tetramethyl-2-heptanone,amylcyclopentanone, 3-methyl-2-(cis-2-pentene-1-yl)-2-cyclopentene-1-on,methylcyclopentenolone, rose ketones, γ-methylionone, α-ionone, carbone,menthone, camphor, nootkatone, benzylacetone, anisylacetone,methyl-β-naphthylketone, 2,5-dimethyl-4-hydroxy-3(2H)-furanone, maltol,7-acetyl-1,2,3,4,5,6,7,8-octahydro-1,1,6,7-tetramethyl naphthalene,muscone, civetone, cyclopentadecanone, and cyclohexedecanone; acetalsand ketals such as acetoaldehyde ethylphenylpropyl acetal, citraldiethylacetal, phenylacetoaldehyde glycerin acetal, and ethylacetoacetateethyleneglycol ketals; ethers such as anethole, Q-naphthylmethyl ether,β-naphthylethyl ether, limonene oxide, rose oxide, 1,8-cineol, andracemic or photoactive dodecahydro-3a,6,6,9α-tetramethylnaphtho[2,1-b]furane; nitriles such as citronellyl nitrile; lactones such asγ-nonalactone, γ-undecalactone, α-decalactone, γ-jasmolactone, coumarin,cyclopentadecanolide, cyclohexadecanolide, ambrettolide, ethylenebrassylate, and 11-oxahexadecanolide; natural essential oils and naturalextracts of orange, lemon, bergamot, mandarin, peppermint, spearmint,lavender, chamomile, rosemary, eucalyptus, sage, basil, rose, geranium,jasmine, ylang-ylang, anise, clove, ginger, nutmeg, cardamom, cedar,Japanese cypress, sandalwood, vetiver, patchouli, and labdanum; andother fragrance materials such as synthetic fragrances.

In addition, the fragrance composition may also contain, as componentsbesides the fragrance ingredients, a surfactant such as polyoxyethylenelauryl sulfate ether; a solvent such as dipropylene glycol, diethylphthalate, ethylene glycol, propylene glycol, methyl myristate, triethylcitrate, or the like; an antioxidant; a coloring agent, and the like.

The compound represented by Formula (1), which has a mint-like aroma andsimultaneously has an aroma of a woody note, a spicy note, a floralnote, or the like, can impart a natural woody note, a spicy note, or afloral note in addition to the mint note when combined with a knownfragrance. Thus, the compound is usefully added to various perfumery andcosmetics, healthcare and sanitary materials as well as to medicinalsupplies, household goods, foods, and the like to thereby impart anaroma thereto. The isobutyric ester according to an embodiment of thepresent invention represented by Formula (1-4) is usefully combined witha known fragrance or the like to thereby impart an aroma because ofhaving a damascone-like fruity-tone, floral-tone, or woody-tone aroma.

Examples of products to which a fragrance composition containing thecompound represented by Formula (1) can be added to impart an aroma andimprove the aroma of the blend object include various products such asperfumery and cosmetics, health and sanitary materials, miscellaneousgoods, beverages, foods, quasi-pharmaceutical products, and medicinalsupplies; the fragrance composition can be used as an aroma componentin, for example, fragrance products such as perfumes and colognes; haircosmetics such as shampoos, rinses, hair tonics, hair creams, mousses,gels, pomades, sprays, and the like; skin cosmetics such as skinlotions, essences, creams, milky lotions, packs, foundations, facepowders, lipsticks, and various make-up products; various health andsanitary detergents such as dish washing detergents, laundry detergents,softeners, disinfecting detergents, anti-odor detergents, indoorfragrances, furniture cares, glass cleaners, furniture cleaners, floorcleaners, disinfectants, insecticides, bleaching agents, bactericides,repellants, and the like; quasi-pharmaceutical products such astoothpastes, mouthwashes, bath additives, antiperspirant products, andperming liquids; miscellaneous goods such as toilet paper and tissuepaper; medicinal supplies; foods, and the like.

The amount of the fragrance composition blended in the product is notparticularly limited, and the amount of the fragrance compositionblended can be selected over a wide range, depending on the type,nature, and sensory benefits of the product to be perfumed. For example,the amount may be 0.00001 mass % or greater, preferably 0.0001 mass % orgreater, and more preferably 0.001 mass % or greater. In the case of afragrance such as perfume or the like, for example, the amount may be100 mass %, preferably 80 mass % or less, more preferably 60 mass % orless, and even more preferably 40 mass % or less.

[Compound Represented by Formula (2)]

A compound according to an embodiment of the present invention isrepresented by Formula (2). The compound represented by Formula (2)below is also referred to as the “isobutyric ester according to anembodiment of the present invention” or the “compound according to anembodiment of the present invention”.

wherein, in Formula (2), R² represents a linear, branched, or cyclicalkyl group having 2 to 5 carbon atoms.

In Formula (2), specific examples of R² include an ethyl group, an-propyl group, an isopropyl group, a n-butyl group, an isobutyl group(2-methylpropyl group), a sec-butyl group (1-methylpropyl group), atert-butyl group, a n-pentyl group, a 1-methylbutyl group (2-pentylgroup), a 2-methylbutyl group, a 3-methylbutyl group, a neopentyl group(2,2-dimethylpropyl group), a 2-methylbutan-2-yl group, a 1-ethylpropylgroup (3-pentyl group), a 3-methylbutan-2-yl group, a cyclopropyl group,a cyclobutyl group, and a cyclopentyl group.

When the R² group has an asymmetric carbon, the compound represented byFormula (2) comprises any one of optical isomers resulting from theasymmetric carbon or a mixture of the isomers at any proportion.

For the isobutyric ester according to an embodiment of the presentinvention, in Formula (2), R² is preferably selected from the groupconsisting of an ethyl group, a n-propyl group, an isopropyl group, an-butyl group, an isobutyl group, a sec-butyl group, a3-methylbutan-2-yl group, and a cyclopentyl group. Additionally, R² isalso preferably selected from the group consisting of an ethyl group, an-propyl group, an isopropyl group, a n-butyl group, an isobutyl group,and a cyclopentyl group.

That is, the isobutyric ester according to an embodiment of the presentinvention is particularly preferably the following compound.

In Formula (2), R² is an ethyl group.

In Formula (2), R² is a n-propyl group.

In Formula (2), R² is an isopropyl group.

In Formula (2), R² is a n-butyl group.

In Formula (2), R² is an isobutyl group.

In Formula (2), R² is a sec-butyl group.

In Formula (2), R² is a 3-methylbutan-2-yl group.

In Formula (2), R² is a cyclopentyl group.

A compound preferred as the isobutyric ester according to an embodimentof the present invention is a compound represented by any of Formulas(2-1) to (2-18) below, and particularly preferred is a compoundrepresented by any of Formulas (2-1) to (2-7) or (2-17).

Note that the isobutyric ester according to an embodiment of the presentinvention is any of compounds represented by Formula (1) excludingmethyl α-propanoyloxyisobutyrate, in which R¹ is a methyl group. Thus,the isobutyric ester according to an embodiment of the present inventionis useful alone as a fragrance and is also useful as an activeingredient for a fragrance composition.

Additionally, the isobutyric ester according to an embodiment of thepresent invention is preferably used as a fragrance and is morepreferably used to impart a mint-like scent. Furthermore, the isobutyricester according to an embodiment of the present invention represented byFormula (2-3) is more preferably used to impart a damascone-likefruity-tone, floral-tone, or woody-tone fragrance.

[Method for Producing Isobutyric Ester According to Embodiment ofPresent Invention and Compound Represented by Formula (1)]

The production method of the isobutyric ester according to an embodimentof the present invention represented by Formula (2) and the compoundrepresented by Formula (1) is not particularly limited and may beappropriately selected from known methods and used.

Examples thereof include a method including reacting anα-hydroxyisobutyric ester with an acylating agent in the presence orabsence of a catalyst to propanoylate the hydroxyl group at theα-position. Examples of the acylating agent to be used includecarboxylic acids such as propionic acid, carboxylic anhydrides such aspropionic anhydride, carboxylic halides such as propanoyl chloride andpropanoyl bromide, and ketene compounds such as methyl ketene. Inaddition, two or more acylating agents selected from these may be usedin combination at any ratio.

The reaction formula when a carboxylic acid, a carboxylic acidanhydride, or a carboxylic acid halide is used is shown as Formula (3)below.

In Formula (3), R represents a linear, branched, or cyclic alkyl grouphaving 1 to 5 carbon atoms. Y depends on the type of the acylating agentand represents, for example, a hydroxyl group, a propanoyloxy group,chlorine, bromine, iodine, or the like.

The reaction formula when a ketene compound is used is shown as Formula(4) below.

In Formula (4), R represents a linear, branched, or cyclic alkyl grouphaving 1 to 5 carbon atoms.

Further, a target α-propanoyloxyisobutyric ester can be produced bytransesterifying an α-propanoyloxyisobutyric ester with an alcohol ofdifferent kinds in the presence of a catalyst. The reaction formula forthis reaction is shown as Formula (5) below.

In Formula (5), R represents a linear, branched, or cyclic alkyl grouphaving 1 to 5 carbon atoms. R′ is not particularly limited as long as itis an alkyl group different from R.

Similarly, a target α-propanoyloxyisobutyric ester can be produced byesterifying α-propanoyloxyisobutyric acid with an alcohol in thepresence of a catalyst. The reaction formula for this reaction is shownas Formula (6) below.

In Formula (6), R represents a linear, branched, or cyclic alkyl grouphaving 1 to 5 carbon atoms.

Known catalysts, reaction methods, reaction conditions, and reactionapparatus can be used as the catalyst, reaction method, reactionconditions, reaction apparatus, and the like to be used for thesereactions, and there are no particular limitation thereon. In addition,as a method for purifying the isobutyric ester according to anembodiment of the present invention represented by Formula (2) and thecompound represented by Formula (1) obtained, a known purificationmethod can be used, and there is no limitation thereon.

EXAMPLES

Hereinafter, the present invention will be described in further detailwith reference to examples, but the present invention is not limited tothese examples.

The reaction performance was evaluated according to the followingexpression.Reaction yield (%)=[(number of moles of product ester in reactionsolution)/(number of moles of raw material ester in solution fed)]×100%<Gas Chromatography (GC) Analysis Conditions>

Apparatus: GC-2010 (available from Shimadzu Corporation, trade name)

Detector: FID

Column: DB-1 (capillary column available from J&W Scientific, Inc.,trade name) (0.25 mmφ×60 m×0.25 μm)

<NMR Spectrum Analysis>

Identification of the ester was performed by ¹H-NMR measurement and¹³C-NMR measurement. The measurement conditions are shown below.

Apparatus: ECA500 (available from JEOL Ltd., trade name)

[¹H-NMR]

Nuclide: ¹H

Measurement frequency: 500 MHz

Measurement sample: 5% CDCl₃ solution

[¹³C-NMR]

Nuclide: ¹³C

Measurement frequency: 125 MHz

Measurement sample: 5% CDCl₃ solution

<Gas Chromatograph-Mass Spectrometry (GC-MS Analysis)>

Identification of the compounds was also performed by determining themolecular weight by GC-MS measurement (chemical ionization method [CI+],high resolution mass spectrometry [millimass]). The measurementconditions are shown below.

GC apparatus: Agilent 7890A (available from Agilent Technologies, tradename)

GC measurement conditions

Column: DB-1 (capillary column available from J&W Scientific, Inc.,trade name) (0.25 mmφ×30 m×0.25 μm)

MS apparatus: JMS-T100GCV (available from JEOL Ltd., trade name)

MS measurement conditions: chemical ionization method

Detector conditions: 200 eV, 300 μA

Reagent gas: isobutane

The exact mass values of fragments detected in the protonated state bythe chemical ionization method and the chemical composition formula thusattributed were described.

Example 1: Synthesis of Methyl α-Propanoyloxyisobutyrate

20.0 g of methyl α-hydroxyisobutyrate (available from Mitsubishi GasChemical Company, Inc.), 26.4 g of propionic anhydride (available fromWako Pure Chemical Industries, Ltd.), 13.4 g of pyridine (available fromWako Pure Chemical Industries, Ltd.), and 2.1 g of4-dimethylaminopyridine (available from Wako Pure Chemical Industries,Ltd.) were loaded in a 200 mL glass round bottom flask equipped with acondenser and a stirrer, and reacted under stirring at room temperaturefor 24 hours. From the GC analysis of the reaction solution, it wasconfirmed that methyl α-hydroxyisobutyrate was completely consumed bythe reaction with propionic anhydride and that methylα-propanoyloxyisobutyrate was obtained at a reaction yield of 96% by thereaction of Formula (7) below. Then, a washing operation was performedthree times with a 10% aqueous solution of sodium hydrogen carbonate andtwice with a saturated aqueous solution of sodium chloride. The washedproduct was dried over magnesium sulfate and then concentrated.Subsequently, distillation was performed under reduced pressure toobtain 22.7 g of methyl α-propanoyloxyisobutyrate (purity by GC analysis(hereinafter, also referred to as GC purity): 99.6%) as the fraction at70 hPa and 107° C.

Reference Example 1: Synthesis of Ethyl α-Hydroxyisobutyrate

In a 300 mL glass flask equipped with a distillation tube, 56.7 g ofmethyl α-hydroxyisobutyrate (available from Mitsubishi Gas ChemicalCompany, Inc.), 33.2 g of ethanol (available from Wako Pure ChemicalIndustries, Ltd.), and 0.92 g of titanium tetraethoxide (available fromWako Pure Chemical Industries, Ltd.) were loaded. A transesterificationreaction was performed under normal pressure with heating and refluxing.The reaction was performed for 96 hours while methanol produced wasextracted out of the system. As a result, ethyl α-hydroxyisobutyrate wasobtained at a reaction yield of 97%. After water was added to thereaction system to inactivate the catalyst, distillation was performedunder reduced pressure to obtain 46.9 g of ethyl α-hydroxyisobutyrate(GC purity: 99.6%) as the fraction at 71 mmHg and 77° C.

Reference Examples 2 to 8: Synthesis of Various α-HydroxyisobutyricEsters

Using the same reaction apparatus as in Reference Example 1, anappropriate amount of methyl α-hydroxyisobutyrate (available fromMitsubishi Gas Chemical Company, Inc.) was transesterified with adifferent alcohol (n-propanol, isopropanol, n-butanol, isobutanol,sec-butanol, 3-methyl-2-butanol, cyclopentanol) in the presence of asuitable catalyst such as a titanium tetraalkoxide and/or sodiumalkoxide, and in some cases in the co-presence of a solvent such ashexane or toluene, under appropriate reaction conditions with heating.The transesterification reaction was completed while methanol producedby the reaction was extracted out of the system by distillation orthrough azeotrope with a reaction solvent under the reaction conditions.The same separation operation as in Reference Example 1 was performed toobtain each of the following α-hydroxyisobutyric ester. The GC purity ofthe obtained isobutyric ester is also shown.

n-Propyl α-hydroxyisobutyrate (GC purity: 99.8%)

Isopropyl α-hydroxyisobutyrate (GC purity: 99.6%)

n-Butyl α-hydroxyisobutyrate (GC purity: 99.9%)

Isobutyl α-hydroxyisobutyrate (GC purity: 99.6%)

sec-Butyl α-hydroxyisobutyrate (GC purity: 99.6%)

3-Methylbutan-2-yl α-hydroxyisobutyrate (GC purity: 99.7%)

Cyclopentyl α-hydroxyisobutyrate (GC purity: 99.8%)

Example 2: Synthesis of Ethyl α-Propanoyloxyisobutyrate

Using a reaction apparatus similar to that of Example 1, a reaction wasperformed using ethyl α-hydroxyisobutyrate prepared in Reference Example1, propionic anhydride (available from Wako Pure Chemical Industries,Ltd.), pyridine (available from Wako Pure Chemical Industries, Ltd.),and 4-dimethylaminopyridine (available from Wako Pure ChemicalIndustries, Ltd.) in appropriate amounts. The operation was performed inthe same manner as in Example 1 to obtain ethylα-propanoyloxyisobutyrate (GC purity: 99.6%) as the fraction at 40 hPaand 102° C. by distillation under reduced pressure. The results of theNMR spectral analysis and GC-MS analysis of the product are shown below.

[Ethyl α-Propanoyloxyisobutyrate]

¹H NMR (500 MHz, CDCl₃) δ 1.14 (3H, t, J=7.5 Hz), 1.25 (3H, t, J=7.0Hz), 1.55 (6H, s), 2.33 (2H, q, J=7.5 Hz), 4.18 (2H, q, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 14.0, 24.6, 27.6, 61.2, 78.0, 172.7,173.4

Exact. Mass 189.12087 (C₉H₁₆O₄, parent peak), 143.06928 (C₇H₁₀O₃)

Examples 3 to 9: Synthesis of α-Propanoyloxyisobutyric Ester

Using a reaction apparatus similar to that of Example 2, a reaction wasperformed using each α-hydroxyisobutyric ester prepared in ReferenceExamples 2 to 8, propionic anhydride (available from Wako Pure ChemicalIndustries, Ltd.), pyridine (available from Wako Pure ChemicalIndustries, Ltd.), and 4-dimethylaminopyridine (available from Wako PureChemical Industries, Ltd.) in appropriate amounts. The operation wasperformed in the same manner as in Example 1 to obtain each ofα-propanoyloxyisobutyric esters described below by distillation underreduced pressure. The GC purity of the resulting esters, thedistillation conditions during the distillation under reduced pressure,and the results of NMR spectral analysis and GC-MS analysis are alsoshown.

[n-Propyl α-Propanoyloxyisobutyrate]

GC purity: 98.3%, distillation condition: 29 hPa, 107° C.

¹H NMR (500 MHz, CDCl₃) δ 0.94 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5Hz), 1.55 (6H, s), 1.62-1.69 (2H, m), 2.33 (2H, q, J=7.5 Hz), 4.08 (2H,t, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 10.3, 21.8, 24.6, 27.6, 66.7, 78.0,172.7, 173.3

Exact. Mass 203.13216 (C₁₀H₁₈O₄, parent peak), 143.07371 (C₇H₁₀O₃)

[Isopropyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%, distillation condition: 40 hPa, 103° C.

¹H NMR (500 MHz, CDCl₃) δ 1.14 (3H, t, J=7.5 Hz), 1.23 (6H, d, J=6.5Hz), 1.53 (6H, s), 2.32 (2H, q, J=7.5 Hz), 5.03 (1H, sept, J=6.5 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 21.5, 24.5, 27.6, 68.5, 78.0, 172.1,173.3

Exact. Mass 203.13301 (C₁₀H₁₈O₄, parent peak), 143.07356 (C₇H₁₀O₃)

[n-Butyl α-Propanoyloxyisobutyrate]

GC purity: 99.5%, distillation condition: 13 hPa, 101° C.

¹H NMR (500 MHz, CDCl₃) δ 0.93 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5Hz), 1.34-1.43 (2H, m), 1.55 (6H, s), 1.58-1.64 (2H, m), 2.33 (2H, q,J=7.5 Hz), 4.12 (2H, t, J=7.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 13.6, 19.0, 24.6, 27.6, 30.4, 65.0,78.0, 172.7, 173.3

Exact. Mass 217.15016 (C₁₁H₂₀O₄, parent peak), 143.07245 (C₇H₁₀O₃)

[Isobutyl α-Propanoyloxyisobutyrate]

GC purity: 99.4%, distillation condition: 19 hPa, 106° C.

¹H NMR (500 MHz, CDCl₃) δ 0.93 (6H, d, J=6.5 Hz), 1.13 (3H, t, J=7.5Hz), 1.56 (6H, s), 1.94 (1H, m), 2.34 (2H, q, J=7.5 Hz), 3.90 (2H, d,J=6.5 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 8.9, 19.0, 24.7, 27.60, 27.63, 71.2, 78.0,172.7, 173.3

Exact. Mass 217.14776 (C₁₁H₂₀O₄, parent peak), 143.07242 (C₇H₁₀O₃)

[Sec-Butyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%

¹H NMR (500 MHz, CDCl₃) δ 0.90 (3H, t, J=7.5 Hz), 1.13 (3H, t, J=7.5Hz), 1.20 (3H, d, J=6.0 Hz), 1.51-1.58 (2H, m), 1.55 (3H, s), 1.55 (3H,s), 2.32 (2H, q, J=7.5 Hz), 4.87 (1H, sext, J=6.0 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.0, 9.5, 19.1, 24.5, 24.6, 27.6, 28.6, 73.1,78.1, 172.2, 173.2

Exact. Mass 217.14670 (C₁₁H₂₀O₄, parent peak), 203.13175 (C₁₀H₁₈O₄)

[3-Methylbutan-2-Yl α-Propanoyloxyisobutyrate]

GC purity: 98.7%

¹H NMR (500 MHz, CDCl₃) δ 0.904 (6H, d, J=6.5 Hz), 1.131 (3H, t, J=7.75Hz), 1.152 (3H, d, J=6.0 Hz), 1.541 (3H, s), 1.552 (3H, s), 1.796 (1H,septd, J=6.88 Hz, 6.0 Hz), 2.327 (2H, q, J=7.5 Hz), 4.760 (1H, qd, J=6.0Hz, 6.25 Hz)

¹³C NMR (125 MHz, CDCl₃) δ 9.12, 16.42, 17.91, 18.18, 24.64, 24.90,27.78, 32.70, 76.23, 78.30, 172.34, 173.36

Exact. Mass 231.16135 (C₁₂H₂₂O₄, parent peak), 161.08692 (C₇H₁₂O₄)

[Cyclopentyl α-Propanoyloxyisobutyrate]

GC purity: 99.8%, distillation condition: 9 hPa, 111° C.

¹H NMR (500 MHz, CDCl₃) δ 1.13 (3H, t, J=7.5 Hz), 1.53 (6H, s),1.58-1.63 (2H, in), 1.67-1.74 (4H, in), 1.78-1.86 (2H, in), 2.32 (2H, q,J=7.5 Hz), 5.19 (1H, m)

¹³C NMR (125 MHz, CDCl₃) δ 23.6, 24.5, 27.6, 32.3, 78.0 (×2C), 172.3,173.2

Exact. Mass 229.14540 (C₁₂H₂₀O₄, parent peak), 1610.08500 (C₇H₁₂O₄)

The results of aroma evaluation performed by perfumers for the variousα-propanoyloxyisobutyric esters obtained by the method described aboveare shown in Table 1.

TABLE 1 Structural formula Aroma evaluation Example 1

Mint-like aroma having a refreshing feeling Woody aroma Clove-like spicyaroma Example 2

Brisk mint-like aroma Spicy aroma Basil-like herbal green aroma Earthyaroma Example 3

Brisk mint-like aroma Anise-like aroma Spicy aroma White floral aromaExample 4

Fresh mint-like aroma Spicy rose-like aroma Fruity and rose-like floralaroma (damascone-like) Example 5

Fresh mint-like aroma Citronella-like aroma Spicy herbal green aromaSweet white floral aroma Example 6

Fresh mint-like aroma Sweet coconut-like aroma Citronella-like aromaLilac-like floral aroma Example 7

Rose-like and hyacinth-like green aroma Rose-like floral aroma Mint-likearoma Example 8

Rose-like and muguet-like floral aroma White floral aroma Lime-likegreen aroma Mint-like aroma having a refreshing feeling Example 9

Fresh mint-like aroma Myrrha-based rose-like floral aroma Greenapple-like fruity aroma Green aroma<Biodegradability Evaluation of Fragrance Material>

One of methods for evaluating biodegradability of a compound is the OECDtest guideline 301 C. In accordance with the method, assessment ofbiodegradability is possible for the compound from the biochemicaloxygen demand and the actual rate of oxygen uptake in an aqueoussolution in which the compound and aerobic microorganisms coexist.

Calculation software “Biowin5” and “Biowin6” is known and used in amethod for easily and accurately estimating the probability ofbiodegradation of the compound in compliance with this test method.

The software is available to the public as one of modules of calculationsoftware called “The Estimations Programs Interface for Windows version4.1”, created by the United States Environmental Protection Agency (EPA)for the purpose of evaluating the environmental effects of chemicalsubstances, and is used in the compound classification for The GloballyHarmonized System of Classification and Labelling of Chemicals (GHS) andthe review of new chemical substances by the United States EnvironmentalProtection Agency. This software was used to evaluate the difference inbiodegradability between existing fragrance materials and the compoundsaccording to an embodiment of the present invention.

Menthol, menthone, and carvone, having a mint note and (E)-α-damasconeand (E)-β-damascenone, having a fruity note, were selected asrepresentative examples of existing fragrance materials similar to thecompounds according to an embodiment of the present invention, andevaluated along with the compounds according to an embodiment of thepresent invention. The SMILES formulas used for input to the softwareand the output results of the probabilities of good degradability by“Biowin5 (linear prediction model)” and “Biowin6 (non-linear predictionmodel)” are shown in Tables 2 to 3. A larger value of the resultsindicates better degradability: for a value of 0.5 or greater, thecompound was rated as having good degradability (symbol “A” in thetable), and for a value of less than 0.5, the compound was rated ashaving low degradability (symbol “B” in the table).

From Table 2 to Table 3, the results obtained show that the compoundsaccording to an embodiment of the present invention were expected tohave good biodegradability with respect to menthol, menthone, carvone,(E)-α-damascone, and (E)-β-damascenone, which were the existingfragrance materials similar to the compounds according to an embodimentof the present invention. The results indicated that the compoundsaccording to an embodiment of the present invention are easilybiodegraded after being released into the environment as fragrances, andthus exhibited a lower impact on the environment.

TABLE 2 Biowin5 Biowin6 Degradation Degradation Examples Structuralformula SMILES probability Score probability Score 1

COC(C(C)(C)OC(CC)═O)═O 1.000 A 0.964 A 2

CC(C(OCC)═O)(C)OC(CC)═O 1.008 A 0.965 A 3

CC(C(OCCC)═O)(C)OC(CC)═O 1.015 A 0.966 A 4

CC(C(OC(C)C)═O)(C)OC(CC)═O 0.866 A 0.917 A 5

CC(C(OCCCC)═O)(C)OC(CC)═O 1.023 A 0.967 A 6

CC(C(OCC(C)C)═O)(C)OC(CC)═O 0.874 A 0.919 A 7

CC(C(OC(C)CC)═O)(C)OC(CC)═O 0.874 A 0.919 A 8

CC(C(OC(C)C(C)C)═O)(C)OC(CC)═O 0.733 A 0.820 A 9

CC(C(OC1CCCC1)═O)(C)OC(CC)═O 0.930 A 0.926 A

TABLE 3 Biown5 Biown6 Comparative Degradation Degradation ExampleStructural formula SMILES probability Score probability Score 1

CC(C)C1CCC(C)CC1O 0.455 B 0.331 B 2

CC(C)C1CCC(C)CC1═O 0.406 B 0.335 B 3

C═C(C)C(C1)CC═C(C)C1═O 0.454 B 0.375 B 4

CC1(C)C(C(/C═C/C)═O)C(C)═CCC1 0.398 B 0.216 B 5

CC1(C)C(C(/C═C/C)═O)C(C)C═CC1 0.378 B 0.213 B

Example 10: Woody-Type Fragrance Composition

A fragrance composition was prepared by adding 37.0 parts by mass of themethyl α-propanoyloxyisobutyrate obtained in Example 1 to 63.0 parts bymass of a fragrance composition having a composition shown in Table 4.

According to the aroma evaluation by perfumers, addition of the methylα-propanoyloxyisobutyrate of Example 1 to the fragrance compositionhaving the composition described in Table 4 added a volume and strengthto the scent, lifted up the citrus, and improved the integrity. As aresult, provided was an elegant woody-note fragrance composition havinga brisk and fresh citrus mint nuance, to which a mint-like refreshingfeeling, woodiness, and spiciness were imparted. The aroma of thisfragrance composition seems to be suitable for perfuming aftershavelotion, men's skin cream, and the like.

TABLE 4 parts by Blend ingredients mass D-Limonene 32.1 Linalool 14.3Decanal (2%) (C-10) 2.9 Lemon oil 2.3 Cyclopentadecanone (10%) 2.0Lavender oil 1.4 10-Undecanal (2%) 1.3 Ambroxide (5%) 1.3 Oakmossabsolute (10%) 1.3 Lilial (50%) 0.8 Styralyl acetate (10%) 0.84-Isopropylcyclohexanol (10%) 0.7 Geranium oil (50%) 0.7 Dimethol (50%)0.7 Coumarin 0.6 Total 63.0 *Blend ingredients in parentheses in thetable were used as a solution diluted with dipropylene glycol. Thefigures represent mass % of the fragrance included in the solution.

Example 11: White Floral-Type Fragrance Composition

A fragrance composition was prepared by adding 21.0 parts by mass of then-propyl α-propanoyloxyisobutyrate obtained in Example 3 to 79.0 partsby mass of a fragrance composition having a composition shown in Table5.

According to the aroma evaluation by perfumers, addition of the n-propylα-propanoyloxyisobutyrate of Example 3 to the fragrance compositionhaving the composition described in Table 5 improved the integrity,increased the stability, and enhanced the intensity of the scent. As aresult, provided was a fragrance composition having a soft and cleanwhite floral aroma, to which brisk mint-like, soft anise-like, and warmspiciness was imparted. The aroma of this fragrance composition seems tobe suitable for perfuming milky lotion, skin cream, body lotion, and thelike.

TABLE 5 parts by Blend ingredients mass Hydroxycitronellal 19.5Phenethyl alcohol 16.8 Cyclopentadecanone 11.5 α,α-Dimethylbenzylcarbinol 9.7 α-Methyl-1,3-benzodioxole-5-propanal 6.2Hexyl salicylate 5.4 Linalool 4.6 α-Terpineol 4.1 α-Ionone 1.1 Total79.0

INDUSTRIAL APPLICABILITY

An isobutyric ester compounds having a propanoyloxy group at theα-position according to an embodiment of the present invention has anexcellent aroma and is expected to be used itself as a fragrance.Additionally, use of the compound as a fragrance ingredient can providea fragrance composition excellent in aroma properties. The composition,when blended in a variety of products, exhibits desired perfumingproperties.

Furthermore, it was shown that the compounds obtained in Examples eachhave excellent biodegradability and a low impact on the environment andare suitable for use.

The invention claimed is:
 1. A fragrance composition comprising acompound, represented by the following formula (2):

wherein R² represents a straight, branched, or cyclic alkyl group having2 to 5 carbon atoms.
 2. The fragrance composition according to claim 1,wherein R² is selected from the group consisting of an ethyl group, an-propyl group, an isopropyl group, a n-butyl group, an isobutyl group,a sec-butyl group, a 3-methylbutan-2-yl group, and a cyclopentyl group.3. The fragrance composition according to claim 1, wherein R² is anethyl group.
 4. The fragrance composition according to claim 1, whereinR² is a n-propyl group.
 5. The fragrance composition according to claim1, wherein R² is an isopropyl group.
 6. The fragrance compositionaccording to claim 1, wherein R² is a n-butyl group.
 7. The fragrancecomposition according to claim 1, wherein R² is an isobutyl group. 8.The fragrance composition according to claim 1, wherein R² is asec-butyl group.
 9. The fragrance composition according to claim 1,wherein R² is a 3-methylbutan-2-yl group.
 10. The fragrance compositionaccording to claim 1, wherein R² is a cyclopentyl group.